From document DE 10 2009 023 498 A1 there is known a parking brake assembly with an emergency unlocking mechanism for a motor vehicle with an electrically driven driving axle. The electric drive is used for transmitting torque to the output shaft in order, thus, to reduce the actuating forces necessary for releasing the locking mechanism. The emergency unlocking mechanism comprises a threaded pin which, by being threaded into a housing of the parking brake assembly, is able to axially displace a pressure element for unlocking purposes.